Silvia Puddu - First ARDENT Workshop Vienna 2012 120/10/2012

ESR_3

S.Puddu

Supervisors: M. Silari, F. Murtas

Nice to meet you

20/10/2012 Silvia Puddu - First ARDENT Workshop Vienna 2012 2

• Name: Silvia Puddu• Born in Cagliari-Sardinia (Italy)• Study: Università degli Sutdi di Cagliari

o Bachelor thesis: Development of a portable system For the test on MWPC at ALICE esperiment

o Master Thesis: Development of a diagnostic system for burning plasma (INFN-LNF/ENEA)

Poster APS 2009 X-ray detector for burning plasmas – S. Puddu , F. Bombarda, G. Pizzicaroli, F. Murtas

Nuclear Instruments and Methods, doi :10.16/j.nima.2009.06.101(2009)

Design of a GEM-based detector for the measurement of fast neutrons. B. Esposito, F. Murtas, R.Villari, M. Angelone, D. Marocco, P. Pillon and S. Puddu

ESR 3

20/10/2012 Silvia Puddu - First ARDENT Workshop Vienna 2012 3

• Study of applications of triple GEM detector

o Beam monitoring for CERF and CNAO

o Beam monitoring for spallation source

o Neutron dosimetry

o Radioactive waste

90°

ESR 3

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• Study of applications of triple GEM detector

o Beam monitoring for mip CERF and CNAO

o Beam monitoring for spallation sources

o Neutron dosimetry

o Radioactive waste

108 107 106 105 104 103 102 10 (eV)

10-7 10-6 10-5 10-4 10-3 10-2 10-1

Photon Time(s)

105

104

F(d

g/d

lnt/

cm2/p

uls

e)

103

102

Neutron flux vs energy

Prompt g flash at ~ 600 ns

~4.7 ms

~63.7 ms

Measurements range

“Slow” photons from several processes

+g from neutrons radiative capture in the beam dump

Results @ n_TOF: ieee 2012

20/10/2012 Silvia Puddu - First ARDENT Workshop Vienna 2012 5C. Guerrero Sanchez, The neutron beam and the associated physics program of the CERN n_Tof facility, ATS seminar

E. Chiaveri et al, CERN n_TOF facility performance report, CERN-SL-2002-053 ECT (2002)

• Particle conversion, charge amplification and signal induction zones are physically separated

• Time resolution depends on geometry and gas: 9.7 ns for Ar-CO2 (70-30)• Spatial resolution depends on geometry (up to 200 m), however is limited by

readout• Dynamic range: from 1 to 108 particles/cm2 s• Effective gain is given by the formula:

iGeff VG

F. Sauli NIM A386 531

M. Alfonsi et al., The triple-Gem detector for the M1R1 muon station at LHCb, N14-182, 2005 IEEE-NSS

70 mm

140 mm 50

mm

31/10/2012

Silvia Puddu IEEE NSS Conference 2012 6

Results @ n_TOF: ieee 2012

• Particle conversion, charge amplification and signal induction zones are physically separated

• Time resolution depends on geometry and gas: 9.7 ns for Ar-CO2 (70-30)• Spatial resolution depends on geometry (up to 200 m), however is limited by

readout• Dynamic range: from 1 to 108 particles/cm2 s• Effective gain is given by the formula:

iGeff VG

F. Sauli NIM A386 531

M. Alfonsi et al., The triple-Gem detector for the M1R1 muon station at LHCb, N14-182, 2005 IEEE-NSS

3mm

1mm

1mm

2mm

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Results @ n_TOF: ieee 2012

Silvia Puddu - First ARDENT Workshop Vienna 2012 820/10/2012

Results @ n_TOF: ieee 2012

How detect fast neutrons

• Neutron converter 60 mm PE + 40 mm Al• Gas mixture Ar-CO2 70%-30%

• Measurements near to the beam dump• Low g sensitivity: HV at 870V gain ~ 300

Neutrons interact with CH2, and, due to elastic scattering processes, protons are emitted and enter in the gas volume generating a detectable signal.

Aluminium thickness ensures the directional capability, stopping protons that are emitted at a too wide angle.

20/10/2012

Silvia Puddu - First ARDENT Workshop Vienna 2012 9

200 m

Low Sensitivity to Photons

Counts

(H

z)

HV scan with n_TOF and Cs137 with a gate of 1 second

HV(V)750 800 850 900 950 1000 1050 11001E+00

1E+01

1E+02

1E+03

Photons

Neutrons

Counts

(H

z)

HV(V)

Working point (870V)

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Delay 2000 ns, HV 870 V, gate 10 ms

Two different intensity beams arrive to the facility

Instantaneous counts (10 msec)

Cumulative counts

y

y

x

x

Constant: 3640 ± 40 Mean1: 5.9 ± 1.8 cmMean2: 5.5 ± 1.8 cm

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Results @ n_TOF: ieee 2012

Silvia Puddu - First ARDENT Workshop Vienna 2012 1220/10/2012

136000± 4000

49000 ± 1000

Beam 1 Beam2

From proton beam monitor

10 ± 3 hits

26 ± 5 hits

From gem neutron monitor

Beam1

Beam2

Mean efficiency 2.0 ± 0.1 e-4

Results @ n_TOF: ieee 2012

13

The FPGA can detect neutrons vs a delay in time allowing to make a time (i.e.

Neutron energy) scan that allows the efficiency vs energy to be measured

(uncertainty ~0.1 ÷1%, ~20% at 10 MeV ) .

100 keV

2 x10-4

3 MeV

10 MeV

13

Number of neutrons acquired

Number of neutrons detected

20/10/2012 Silvia Puddu - First ARDENT Workshop Vienna 2012

Results @ n_TOF: ieee 2012

14

TANKS

1420/10/2012 Silvia Puddu - First ARDENT Workshop Vienna 2012